In recent self-congratulatory pronouncements, the U.S. Army heralded two "milestones" in its battle to bring an end to a frightening era of warfare.

In April, the Army announced it had destroyed all of the "non-stockpile," or non-functioning, weapons it had declared nationwide when the United States entered into a treaty known as the Chemical Weapons Convention. Last week, officials at Utah's Deseret Chemical Depot said they had destroyed the last mustard agent-filled munitions in their arsenal.

But in both cases, the Army left out a big, dirty and dangerous part of the picture: Thousands of munitions -- many of which still hold the remnants of deadly chemical agents -- have been left, poorly protected and broadly unaccounted for, in Utah's vast west desert.

The weapons have never been declared to treaty partners. And the Army has no idea when, or if, it will ever do so.

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'An environmental nightmare' » Just to the south of Deseret's colossal, modern weapons incinerator lies a scene worthy of a post-apocalyptic movie set.

Decades worth of toxic military trash -- leaking paint cans and broken fire extinguishers, bulging oil drums and shattered tear gas canisters -- fill ditches the size of swimming pools. Grenades, explosive fuses and cluster bombs litter the ground. In some areas, the soil has a green hue; military environmental experts believe that's where napalm was dumped.

But the pièce de résistance is an artificial mountain of charred mortar shells, many of which are thought to carry the hardened remnants of one of the most vile weapons ever invented.

First used in warfare by the German military during World War I and more recently by Saddam Hussein in the notorious Anfal campaign against the Kurds in northern Iraq, mustard gas causes severe blistering, disfigurement and, when inhaled, can damage the lungs or other organs. Exposure to mustard gas increases the risk of cancer, respiratory disease and birth defects in offspring.

Such weapons have met widespread international condemnation. And the U.S. military spent decades denying the extent of its testing of mustard and other weapons of mass destruction in Utah.

But since entering into the treaty, the military has been remarkably candid about the Deseret disaster, known as the East Demilitarization Area, where the Army dumped and burned its weapons from 1945 to 1978. Army officials speak openly about the so-called "solid waste management unit" at public meetings in nearby Tooele. They have invited some members of the public to tour the site, where the mustard-filled mortar shells have rested in plain sight since being discarded during the Cold War. The dump is spread out across thousands of acres -- and protected by little more than a cattle fence.

"This is an environmental nightmare," said Troy Johnson, Deseret's environmental program manager, during a tour of the dump last fall.

While the U.S. is spending billions of dollars to eliminate conventional weapons dumps in Iraq, environmentalists say this virtually unregulated toxic waste dump stands as a hallmark to misplaced priorities.

"This is both shocking and sadly par for the course," said Vanessa Pierce, executive director of the Healthy Environment Alliance of Utah. "The federal government's attitude about the West, for so long, has been that it is a good place to dump its trash...but this is a new level of negligence."

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'We can't say for sure' » Army officials note that the weapons dumped in Utah's desert couldn't be dropped into a mortar tube or loaded into a rocket. "Non-stockpile" is the technical term for such discarded munitions.

But that alone doesn't exempt the weapons from the treaty. Under the terms of the convention, any pieces "recovered" from places like the Deseret dump must be acknowledged and destroyed.

What constitutes a recovered weapon, however, appears to be a matter of semantics, budgets and national priorities.

Only about 1,200 non-stockpile munitions -- mostly weapons captured from enemy nations during World War II -- were declared to Russia and other treaty partners when the convention went into effect in 1997. Those are the weapons that, 13 years later, the Army is crowing about having destroyed from a small number of sites outside Utah.

About 1,200 more weapons pieces have been recovered since then as the military has cleared land once used for testing, said Chemical Munitions Agency spokeswoman Karen Jolley Drewen. "And we're working on destroying those now," she said.

How many weapons have yet to be recovered? "I don't know," Drewen said.

No one does.

The Army has identified 224 potential burial sites -- including 48 in Utah. But there has been no estimate of how many potential chemical munitions those sites hold.

At the Utah site alone are "hundreds of thousands of rounds," according to Johnson, the Deseret environmental program manager. In order to declare the weapons safe, under the treaty, "we would have to go through every one to make sure they are empty," he said.

"Until those pieces are recovered, we can't assess them and see what they are," Drewen said. "We may have a real good idea of what they are, but we can't say for sure."

And the Army has little incentive to do so.

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'Until they're dug up' » Under its treaty obligations, the U.S. has until 2012 to complete the destruction of its chemical arsenal, tightly guarded at Deseret and other sites. No one believes it will hit that mark -- or even come close. Army officials say it may take another decade or longer to destroy the chemical munitions the U.S. declared under the convention.

And that's a pretty good incentive not to attempt anything resembling recovery of the munitions at Deseret, said Lenny Siegel, director of the Center for Public Environmental Oversight. "Places like Deseret aren't covered under the treaty until they're dug up," said Siegel, who studies chemical-weapons issues for the center. "So of course there's a reticence by the military of doing anything."

But even if they were inclined to do so, Army officials say they don't know how they would clean up the Utah dump.

"Deseret Chemical Depot is not unique in its past practices for disposal of munitions," said Deseret's communications chief, Alain Grieser. "Similar disposal operations were conducted at many military installations around the country over the same time period. However, the unique situation at DCD is that we have a combination of conventional and chemical agent munitions disposed in the same areas."

The Army made an effort to collect the munitions from the site for destruction in the 1980s, Grieser said, but ultimately abandoned the task when it became clear that the bomb-by-bomb effort was too dangerous to continue, given the tremendous amount of unexploded ordnance littering the ground.

The current thinking is to employ robots -- officials acknowledge that Disney's Wall-E often comes to mind-- to sort and collect the weapons. But that effort won't likely begin for years to come, if it does at all.

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'Let sleeping dogs lie' » Given the years that have passed, and the dangers involved, Siegel said it might be best to just "let sleeping dogs lie" -- though with one important caveat: "The argument I would make is that there needs to be an effort made to determine whether there is a pathway to human exposure," he said.

The Army has done sporadic monitoring of groundwater underneath the dump, which rests at nearly a mile above sea level. From the limited data it has collected, the water appears to be moving away from population centers like Salt Lake City and Tooele, though monitors say they'll need years of additional data to know for sure.

Pierce, the Healthy Environment Alliance leader from Utah, says she is troubled but not surprised by the Army's lack of certainty, despite the decades it has had to study the dangers. "It's not unlike the Army," she said, "not to have an exit strategy."

mlaplante@sltrib.com / blogs.sltrib.com/military